Large animal models of human disease are indispensible for the development of relevant preclinical therapeutic protocols. Gene inactivation and gene conversion are powerful approaches for creating genocopies of alleles that cause disease in patients and for the modification of genes for biomedical materials development. A DNA double strand break (DSB) at a desired genome location is a flexible substrate for genome engineering, enabling; mutation of a target sequence, targeted integration of transgenes, or the stimulation of gene conversion by homologous recombination (HR) with a repair template. Consequently, the tools for genome engineering are rapidly converging on the concept of DSB induction using a variety of technologies, including the widely publicized Zinc-Finger Nucleases (ZFN) and Meganuclease (MGN) platforms. While both MGN and ZFN are efficient and reasonably precise, significant limitations in targetable sites, difficulty in developing new enzymes, and a constrained IP landscape limit their widespread commercial application. The recently described TAL effector nucleases (TALENs) are a novel DSB-inducing platform that appears to be easier to deploy and with a greater flexibility in target site selection, since their modular DNA binding motifs enable localization of nuclease activity to a broad range of targets. Recombinetics proposes to investigate enablement of TALENs for gene inactivation and, in combination with RCI technologies to stimulate gene conversion in livestock cells and embryos. The studies proposed here will establish a new paradigm for the genetic modification of artiodactyls (pigs, sheep, and cattle) for use as large animal models of human disease and the production of biomedical materials. PUBLIC HEALTH RELEVANCE: Large animal models of human disease are indispensible for the development of relevant preclinical therapeutic protocols. We propose to investigate enablement of TALENs for gene inactivation in livestock cells and, in combination with RCI technologies to stimulate gene conversion in livestock cells and embryos. The studies proposed here will establish a new paradigm for the genetic modification of artiodactyls (pigs, sheep, and cattle) for use as large animal models of human disease.